According to Suffolk County detectives, the holdup happened at a TD Bank branch located on Route 112 at around 9 a.m.
A suspect entered the bank, approached the teller and gave verbal demands, police said. The teller complied with the robber's demands and handed over the cash.
The woman fled on foot and was last seen heading west on Southaven Avenue.
The suspect is described as white, in her early to mid 30s, approximately 5 feet 6 inches tall with blond hair in a ponytail. At the time of the robbery, she was wearing sunglasses, a dark top, white pants and sneakers.
Anyone with information about this incident is urged to call to Crime Stoppers at 1-800-220-TIPS. All calls will be kept confidential.